The invention relates generally to an orthopedic device of the type disclosed in Co-Pending application Ser. No. 07/845,650 filed Mar. 4, 1992 and assigned to the present assignee. The orthopedic devices of the present invention and of the co-pending application are in the form of knee braces for controlling ligament instability, each of the braces having upper and lower cuffs joined together by specially designed polycentric hinges of the type described, for example, in Co-Pending application (K-3538).
A typical orthopedic knee brace of the type with which the present invention is concerned is described, for example, in U.S. Pat. No. 4,966,133 - Kausek. As pointed out in that patent, when the ligament surrounding the knee has been traumatized by injury or by surgery, a supporting brace is commonly used to provide stability to the knee while still permitting movement of the knee. The brace must provide stability when forces are applied to the knee in the medial and lateral (side) planes, and in the anterior (front) and posterior (rear) planes. In addition, the brace must provide rotational stability to prevent excessive axial rotation of the tibia with respect to the femur. The brace must also prevent forward movement of the tibia with respect to the femur, a function provided in the normal knee by the anterior cruciate ligament.
As pointed out in Co-Pending application Ser. No. 07/845,650, a problem encountered in the prior art knee braces is the tendency, particularly for the upper cuff which surrounds the side of the wearer, to slip down along the thigh. The cuffs are normally held in place by straps with VELCRO fasteners, and in view of the slippage tendency, it is often difficult to adjust the straps for optimum effect and comfort, without the tendency for the upper cuff to slip down due to muscle action.
The brace disclosed in the Co-Pending application Ser. No. 07/845,650 includes a simple means which is easily adjustable to assure that the side cuff may be mounted for optimum effect and comfort and still be held firmly in place without excessive slippage despite muscle action of the wearer. The foregoing is achieved in the brace of the Co-Pending application by mounting one or more air pillows between the side of the wearer and the cuff, and by providing a miniature pump coupled to the air pillows. The pump permits the wearer to pump the air pillows to a desired inflated condition to hold the cuff firmly in place, without affecting the comfort of the wearer.
The brace of the present invention is of the same general type as the brace disclosed in the Co-Pending application Ser. No. 07/845,650. However, the brace of the present invention is more effective in preventing slippage in that it includes a pair of air pillows which are mounted on the internal surface of the upper cuff in positions to be located on the opposite sides of the femur of the wearer within the medial and lateral femur hollows and engaging the condyles (knuckles) of the femur. Accordingly, when the air pillows are inflated, the condyles act in a positive manner to prevent any slippage of the upper cuff downwardly, and cause the upper cuff to be held firmly in place.